The conventional video game machine has a cross-shaped key switch on a controller thereof so that the object displayed is moved by the operation of the cross key switch. Such a cross key switch permits only limited direction of movement control to be designated for the object. The speed of movement can not be designated with a conventional cross switch.
There also is a method for varying the moving speed of the object as a function of the length of the time period over which the cross key as stated above is being depressed. In such a method, acceleration or deceleration is controlled for the object at a constant acceleration rate or a constant deceleration rate by each constant depression time period. Although, in this method, the moving direction and the moving speed of the object can be controlled even by using a cross switch, there exists the disadvantage that the object moving speed is varied merely at a constant rate of acceleration or deceleration as determined by software based calculations, so that it is impossible to arbitrarily control the speed of movement. Furthermore, the speed is determined by the period of key depression time, which requires that the cross key has to be depressed for a certain period or longer, resulting in poor responsiveness.
Under such circumstances, the applicants' assignee has proposed in Japanese Provisional Utility Model Publication No. H2-41342, laid open to the public on Mar. 22, 1990, a cross switch having three contacts arranged in one direction on a cross key thereof so that the moving speed, besides the moving direction, is varied for the object by the utilization of changing the turning-on of contacts depending upon the d cross key expression amount.
In this prior art, however, the direction of movement is limited to four directions of upper, lower, left and right (and intermediate directions thereof), and the speed of movement is varied only between three stages of speed. That is, in this prior art there still exists significant limitations in controlling the moving direction and the moving speed.
Although there are already known game machines employing an analog joystick for a control lever of an aircraft, such an analog joystick is typically used for controlling the inclination of the aircraft, and wherein control is impossible for the moving direction or the moving speed.
It is therefore an object of the present invention to provide an image processing system which is high in responsiveness and capable of controlling the moving direction and the moving speed of a player controlled character (object operable object).
The present invention is directed to a three-dimensional image processing system including an image processing apparatus connected to a display to generate image data for displaying an object existing in a three-dimensional space on the display according to a stored program, and an operating device including an operating member having a base end rotatably supported and a free end operable by an operator, so that the image data is varied in accordance with movement of the operating member. The operating device includes inclination amount data output circuitry which detects an inclination amount of the operating member to output inclination amount data. The exemplary image processing apparatus includes direction determining hardware and software which determines a moving direction of the object in three-dimensional space based on the inclination amount data; moving amount determining hardware and software which determines a moving amount of the object within one display frame; position determining hardware and software which determines object position in the three-dimensional space in accordance with the moving direction and the moving amount; and an image data output circuitry which outputs image data for displaying the object on the display at a position controlled by the position determining hardware and software.
The operating device is, for example, an analog joystick, which includes a base end supported rotatably with a given angle range and a free end for being operated by an operator so that the operating member is inclined to arbitrary directions in accordance with operator operation. For example, an inclination amount data output circuitry such as an X counter and a Y counter detects the amount of inclination of the operating member to output inclination amount data.
The image processing apparatus includes a program storing memory, wherein the program storing memory is preferably an external storage device detachably attached to the image processing apparatus main body. Direction determining circuitry and moving amount determining circuitry comprised for example of a CPU under control of the stored program respectively determine moving direction of the object in the three-dimensional space and moving amount of the object to be moved in one display frame, based on the inclination amount data from the operating device.
Specifically, count values of an X counter and the Y counter are converted by normalizing into a UV coordinate frame. The CPU determines the inclination amount (L) and the inclination direction (tan.sup.-1) by the UV coordinate value (u, v). The direction determining circuitry is, for example, the CPU, which determines under program control the moving direction of the object based on the inclination direction (tan.sup.-1) thereof and the point of view (camera angle) at which the object is considered to be "photographed" in the three-dimensional space. The moving amount determining circuitry is, for example, the CPU, which determines under program control the moving amount of the object within the one display frame, i.e., the moving speed, based on the inclination amount (L) and the maximum speed (max-speed).
Therefore, the position determining circuitry determines the position of the object in three-dimensional space in dependence upon the moving direction and the moving amount. Consequently, the image data output circuitry outputs image data for display of the object at the position thus determined.
In accordance with the present invention, the operation of one operating device such as an analog joystick provides control of the moving direction and the moving amount (moving speed) of the object.
Another embodiment of the present invention relates to image processing apparatus which generate images using polygons. When a displayed character which is created by polygons moves at high speed, and when it is necessary to process an extremely large number of polygon operations within a specified time, serious problems may result. Under such circumstances, if the number of polygons to be processed exceeds the operation capacity of the image processing apparatus, the image processing apparatus may fail to timely process the image data. As a result, the displayed image may, for example, erroneously appear to be moving in slow motion.
The image processing apparatus of the present invention may be advantageously used when the increase in the number of polygons due to the elevation of the character moving speed or the like exceeds the operation capacity (hereinafter called limit detection). It is a feature of the image processing apparatus of the present invention that the number of polygons for generating a character is selectively decreased, e.g., when the limit is detected to avoid slow motion due to failure in processing. More particularly, according to the present application, when it is necessary or desirable to decrease the number of polygons, the number of polygons is decreased on a priority basis in the area where a rough image is more easily tolerated, such as the body of the character, and is not decreased to the extent possible in the area where a rough image is more noticeable, such as the face.
In accordance with this further embodiment, the number of polygons utilized to display a player-controlled character is modified depending upon the speed of movement of the character, whereby the number of polygons is reduced at higher speed. At low level speeds, the character is drawn with a predetermined number of polygons and at higher level speeds the character is drawn with a reduced number of polygons, except that the polygons used for drawing the face remains the same as at the first level speed. In this fashion, the character is simulated in a manner designed to appear to be most realistic to the user, who is more likely to focus on the character face, rather than the body during animated character motion. Thus, in the present application, since the number of polygons is decreased sequentially from the less noticeable area to the more noticeable area, depending on the moving speed of the character, processing failure and slow motion erroneous displays can be prevented without recognition of a rough image by the user.
The above and other objects, features, aspects, and advantage of the present invention will become more apparent from the ensuing detailed description of the present invention when taken in conjunction with the accompanying drawings.